Cytophysiology and innervation of gonadotropic cells in the pituitary of the Black Molly (Poecilia latipinna)

Abstract

In the male black molly, poecilia latipinna, morphological and functional aspects of the gonadotropic (GTH-)cells have been studied at the ultrastructural level. The cells exclusively occupy the ventral and lateral areas of the meso-adenohypophysis. In the black molly there is evidence of the presence of only one type of gonadotropic cell. In the GTH-cells of most specimens, the rough endoplasmic reticulum is weakly developed. The secretory vesicles are characterized by cores with varying diameters; this variation was not observed in the secretory vesicles of the other types of pituitary cells, except in the TSH-cells. After applying a histochemical method for the demonstration of polysaccharides, small black deposits appear in the core of the secretory vesicles of the GTH- and TSH-cells only; this indicates the glycoproteinaceous nature of the hormones produced in these cells. Male black mollies treated with methyl-testosterone have significantly smaller GTH-cells and a lesser number of secretory vesicles and mitochondria in these cells. GTH-cell activity in Poeciliinae may be thus influenced by androgens by means of a negative feed-back mechanism. The GTH-cells are innervated by both type A and type B neurosecretory fibres. There are indications that the type A fibres may originate from the pars lateralis cells of the nucleus lateralis tuberis; the origin of the type B fibres is uncertain.

Etude du contrôle hypothalamique de la fonction gonadotrope chez Gambusia sp. (poisson téléostéen) par la technique des greffes

“…Jusqu'à présent, nous n'avons pu obtenir la reprise de la vitellogenèse après autogreffe d'hypophyse dans la musculature caudale, qu'au moment de la reprise de l'activité sexuelle de l'espèce, au début du printemps. Il (Zambrano, 1972 ;Ekengren, 1975 (Peute et al, 1976). Les fibres B proviendraient du noyau latéral de tuber qui paraît être impliqué dans le contrôle de la reproduction (Péter, 1970 ;Zambrano, 1972 …”

Immunohistochemical cross-reaction of anti-mammalian LH-RH in lower vertebrates

“…In teleosts this hypothesis is mainly based on observations of correlative changes in environmental factors, hypothalamic nuclei and adenohypophysial activity (Peter, 1970 ;Ball et al, 1972). In addition, neurosecretory fibres, originating from the hypothalamus, are known to terminate on glandular cells of the adenohypophysis, on neighbouring capillaries, and on membranes of intracellular spaces (Zambrano, 1972 ;Peute et a/., 1976). These observations and the results of lesioning experiments (Peter, 1970) focussed attention on the nucleis lateralis tuberis (NLT) as the source of a gonadotropin releasing hormone (GRH) in teleosts.…”